Proc 5th Intl Coral Reef Congress (Tahiti) (1985), 5, 15-20
Response of Halimeda metabolism to various environmental parameters.
Kay M Abel and Edward A Drew
Australian Institute of Marine Science, PMB No 3, MSO, Townsville,
Queensland 4810, Australia
Abstract
The physiological responses of several Halimeda species to changes in irradiance, temperature and nutrient supply have been determined in a combination of laboratory and in situ experiments. The species used were those most frequently encountered in both reefal and inter-reefal environments in the Great Barrier Reef Province.
The oxygen method (light and dark incubations) has been used to measure photosynthesis and respiration rates using laboratory cultured material, freshly collected material incubated on board ship, and material incubated in situ on reefs to 28 m depth. Carbon 14 and calcium 45 tracer techniques were also used in the in situ incubations to measure carbon fixation and calcification data.
Laboratory experiments to investigate nitrate and phosphate uptake and accumulation are also reported together with growth experiments at enhanced nutrient levels. The results are discussed in terms of metabolic rates required to maintain known growth rates on reefs and also the rates of production of dead segments required to account for accumulation of Halimeda gravel deposits of known age, particularly in areas of potential intrusion of cold, nutrient rich water onto the GBR.